Vibrationally Assisted Delayed Fluorescence (VADF) in Perovskite Quantum Dots for Harvesting Delayed Fluorescence
Pradeep KR a, Ranjani Viswanatha a
a JNCASR Jawaharlal Nerhu Centre for Advanced Scientific Research, Jakkur, BENGALURU, India
Materials for Sustainable Development Conference (MATSUS)
Proceedings of Online nanoGe Fall Meeting 20 (OnlineNFM20)
#PerNC20. Perovskite II - Colloidal Nanocrystals: Synthesis, Spectroscopy, Theory and Applications
Online, Spain, 2020 October 20th - 23rd
Organizers: Gabriele Raino, Maryna Bodnarchuk and Oleksandr Voznyy
Contributed talk, Pradeep KR, presentation 166
Publication date: 4th October 2020

Opto-electronic devices based on all-inorganic perovskite systems are an energy-efficient source of lighting due to their high photoluminescence quantum yield (QY). However, dominant surface trapping continues to plague the field, despite their high defect tolerance, as evidenced by the several fold improvements in the external quantum efficiency of perovskite nanocrystals (NCs) upon appropriate surface passivation or physical confinement between high bandgap materials. Here, we introduce the concept of drip-feeding of photo-excited electrons from an impurity-induced spin-forbidden state to address this major shortcoming.  An increased and delayed (about several milliseconds) excitonic QY, and density functional theory establish the electron back-transfer signifying efficient recombination.  We term this electron back-transfer from Mn2+ to the host conduction band in this prototypical example of Mn-doped CsPbX3 (X = Cl, Br) NCs through vibrational coupling as Vibrationally Assisted Delayed Fluorescence (VADF).

References:

1. Pradeep K. R., Debdipto Acharya, Priyanka Jain, Kushagra Gahlot, Anur Yadav, Andrea Camellini, Margherita Zavelani-     Rossi, Giulio Cerullo, Chandrabhas Narayana, Shobhana Narasimhan, and Ranjani Viswanatha, Harvesting Delayed Fluorescence in Perovskite Nanocrystals Using Spin-Forbidden Mn d States, ACS Energy Letters 2020 5 (2), 353-359

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